Method and apparatus for controlling record and reproduction of optical record medium

ABSTRACT

Disclosed is a method and apparatus for controlling the record and reproduction of optical record medium in which plural non-record regions having different phase are arranged between recordable data regions for the distinction in the shape of the data region. The method and apparatus performs the servo using focus error signal and tracking error signal averaged by the low pass filter at the header region of the optical disc. Especially, the tracking servo is performed by holding a fixed DC off-set value at the header region existing on the L/G switching or holding the tracking error value of the previous same track region. As a result, the exact header region is detected, the track sliding phenomenon is removed, and the tracking servo is stabilized, resulting in preventing the degeneration of the record and reproduction characteristics.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of co-pending application Ser. No.09/572,500 filed on May 18, 2000, and for which priority is claimedunder 35 U.S.C. §120; and this application claims priority ofApplication No. P1999-17869 and P1999-28983 filed in Korea, Republic ofon May 18, 1999 and Jul. 16, 1999, respectively under 35 U.S.C. §119;the entire contents of all are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to an optical record mediumsystem, and more particularly to a method and apparatus for controllingrecord and reproduction of an optical record medium where a headerregion that is plural non-record regions having different phase isarranged between recordable data regions for the distinction in theshape of the data region.

2. Description of the Related Art

Generally, there is an optical record medium with freely and repeatedlyrecordable capability, for instance, a rewritable compact disc(CD-RW), arewritable digital versatile disc(DVD-RW, DVD-RAM, DVD+RW), etc.

The rewritable digital versatile disc, especially DVD-RAM has a signaltrack consisting of a land and groove structure. Data can be recorded ona track of the land and groove as well as a track of the land or grooveor can be reproduced through the track of the land and groove as well asthe track of the land or groove.

FIG. 1 is a block diagram of a record and reproduction apparatus forthese optical discs.

Referring to FIG. 1, the apparatus includes an optical pick-up 102. Theoptical pick-up 102 allows the light beam concentrated on an object lensto be placed on the signal track of an optical disc 101 according to thecontrol of a servo control part 107, and the light beam that isreflected on a signal record face of the signal track and is thenincident to be concentrated on the object lens and to be incident intoan optical detector for the detection of a focus error signal and atracking error signal. The optical detector includes a plurality oflight detecting elements. An electrical signal that is proportional tothe light amount obtained by each of the light detecting elements isoutput to a RF & servo error generating part 103.

If the optical detector, as shown in FIG. 2, consists of four opticaldetectors of PDA, PDB, PDC, and PDD that are divided into a specific,for example, four sectors along the signal track direction and theradial direction, the optical detector outputs to the RF & servo errorgenerating part 103 electrical signals of a, b, c, and d that areproportional to the light amount obtained by each of the opticaldetectors of PDA, PDB, PDC and PDD.

The RF and servo error generating part 103 makes a combination of theelectrical signals of a, b, c and d to generate an RF signal that isnecessary for the data reproduction, and a tracking error signal and afocus error signal that are necessary for the servo control.

Here, the RF signal is obtained by adding all of the electrical signalsof a, b, c and d(a+b+c+d). The tracking error signal can be obtained byprocessing a signal of (a+d)−(b+c) referred to as Read Channel 2signal(R-ch2).

If the optical detector is divided into two sectors along the trackdirection, the optical detector detects the RF signal (=I1+I2) and theR-ch2 from both photo diodes I1 and I2. In other words, a+d of FIG. 2corresponds to I1 and b+c corresponds to I2.

Then, since there is no information in an initial disc in case of theDVD-RAM 101, it is impossible to control and record the disc.

To this end, to perform the tracking control, a disc track is made inthe land and groove, information is recorded along a correspondingtrack, and control information for sector address, random access androtational control are additively recorded on the disc, thereby allowingthe tracking control to be performed even for a vacant disc on whichinformation signal is not recorded. The control information can berecorded at an initial position of each sector by pre-formatting theheader region.

In case of DVD-RAM, the header region that is pre-formatted at theinitial position of each sector consists of four header fields(header 1field˜header 4 field). The header 1 and 2 fields and the header 3 and 4fields are crossed about the track center. FIG. 3 is one example of sucha cross arrangement and shows a constitution of a header field for thefirst sector in one track.

The above constituted header, however, badly affects on reallygenerating a servo error signal such as tracking error signal and focuserror signal. In other words, the servo error signal read on the headerregion is distorted depending on the header constitution, which isfollowed by a difficulty in controlling the servo signal.

Accordingly, in case of DVD-RAM, there is an effort for decreasing aninfluence of the header by holding respective servo error signals, forinstance, tracking error signal and focus error signal in order togenerate servo error signal and control the generated servo error signalwith stability and thereby controlling the servo.

That is, a focus sampling & holding part 104-1 of a sampling & holderpart 104 samples a focus error signal(FE) and holds the sampled focuserror signal at the header region, and a tracking sampling & holdingpart 104-2 samples a tracking error signal(TE) and holds the sampledtracking error signal at the header region, thereby allowing the lightbeam not to be deviate from the track center.

A selection part 104-3 selects the focus error signal and the trackingerror signal which are sampled and held by the focus sampling & holdingpart 104-1 and the tracking sampling & holding part 104-2, respectivelyas a header mask signal(HDM) representing the header region is outputfrom a header mask & L/G switching signal generating part 106, i.e., atthe header region, while the selection part 104-3 selects a focus errorsignal and a tracking error signal that do not pass through the focussampling & holding part 104-1 and the tracking sampling & holding part104-2 and outputs the selected signals to an off-set control part 105 incases other than the above circumstance, i.e., at the record region.

This means that the focus servo and the tracking servo are performed atthe header region not using tracking error signal and focus error signalthat are detected in real but using a holding value. Here, there aresome kinds of methods for detecting the header region. The header mask &L/G switching signal generating part 106 detects this header region,generates the header mask signal(HDM) representing the header regionwithin the detected header region, and outputs the generated header masksignal to the selection part 104-3 of the sampling & holding part 104.

Here, the header region can be detected by slicing the RF signal orR-ch2, or by generating IP1 and IP2 signals from R-ch2 and then making acombination of the IP1 and IP2 signals. That is, since the header 1 and2 fields and the header 3 and 4 fields are crossed about the trackcenter, IP1 and IP2 signals can be detected by slicing R-ch2 of theheader region. For instance, assuming that IP1 signal is output when thetrack center is set to be the slice level and the R-ch2 has a levelhigher than the slice level and IP2 signal is output when the R-ch2 hasa level lower than the slice level, phases of the IP1 and IP2 signalsare changed depending on whether the present operation track is land orgroove. In other words, either IP1 signal or IP2 signal can be firstlyplaced depending on whether the present operation track is land orgroove.

Meanwhile, the tracking error signal in the land has an inversionrelation to the tracking error signal in the groove. In other words, thetracking error signal detected in the land has an inversion phaserelation compared with the tracking error signal detected in the groove.Thus, in order to normally follow the track in both of the land and thegroove, tracking error signals respectively obtained in the land and thegroove have the same phase with each other.

Also, there exists a difference in a DC off-set that is basically,respectively contained in the land and the groove due to a difference indepth between the land and the groove. The DC off-set is an amount thatis generated in the terms of signal due to the difference in depthbetween the land and the groove. Although the focus and the tracking areappropriate at the track of the land, de-focus or de-track may begenerated when the focus and the tracking are identically applied to thetrack of the groove. In addition, when the focus and the tracking areadjusted to the track of the groove, the de-focus and the de-track canbe likewise generated at the track of the land due to a difference indepth between the land and the groove.

The off-set control part 105 is provided for this reason. A focusoff-set control part of the off-set control part 105 adjusts the focuserror off-set that is appropriate for each of the groove and the land toperform a normal focus servo. Also, the tracking off-set control part105-2 adjusts the tracking error off-set that is appropriate for each ofthe groove and the land to perform a normal tracking servo andsimultaneously inverses the tracking error signal that is detected atthe land.

And, the tracking off-set control part 105-2 is operated depending onswitching signals of L/Gsw output from the header mask signal & L/Gswitching signal generating part 106: i.e., the tracking off-set controlpart 105-2 selects the focus error signal whose off-set is adjusted tothe land and an inverted tracking error signal when the present signaltrack represents the land, while the tracking off-set control part 105-2selects the focus error signal whose off-set is adjusted to the grooveand the tracking error signal. The selected signal is output to theservo control part 107. Thus, the servo control part 107 performs thefocus servo and the tracking servo whose off-sets are adjusted to theland through a focus/track(F/T) servo driving part 108, or performs thefocus servo and the tracking servo whose off-sets are adjusted to thegroove. These behaviors are determined by the L/G switchingsignals(L/Gsw). Here, the L/G means that the signal track is convertedfrom the land to the groove or from the groove to the land.

That is, according to whether the present track is the land or thegroove, IP1 signal or IP2 signal may precede. Thus, the header mask &L/G switching signal generating part 106 determines that the presenttrack is the land or the groove considering which one of the land or thegroove signal precedes and inverts the L/G switching signal (L/Gsw) andoutputs the inverted signal to the off-set control part 105.

At this time, as one method for holding the focus error signal and thetracking error signal during the header region period, there is a methodfor sampling and holding the focus and tracking error values of rightbefore the header region starts. Also, the header region existing on theL/G switching is covered with header mask such that the light beams donot deviate from the track center, a focus and tracking error prior tothe header region value is sampled and is held during the header regionperiod.

However, since the sample & holder 104 is made of analog circuit, a dropoccurs due to the charging and afterwards discharging of RC time delay,thereby generating a transient response. Also, since the tracking errorsignal of the previous track(prior to inverting) is sampled/held at theheader region that exists on L/G switching, and inverted to therebyperform the tracking servo, there occurs a drawback increasing the trackerror.

For example, at the header region existing during the switching from theland to the groove, the tracking error signal detected at the land issampled/held and is switched to the groove, and simultaneously theholding value is inverted to perform the tracking servo. At this time,since the land and the groove have a different DC off-set due to thedifference in depth between the land and the groove, the tracking errorsignal is bounded by the off-set amount of the land when the land isswitched to the groove as shown in FIG. 5 and thereby the servo becomesunstable. In other words, the off-set of the land highly increases bythe inverting.

Also, at the header region existing when the groove is switched to theland, the tracking error signal detected in the header region is sampledand held, and thereafter is switched to the land, and simultaneously theholding value is inverted, the tracking servo is performed. Likewise, atthe header region existing when the groove is switched to the land, thetrack error increases by the above mentioned reason when the groove isswitched to the land as shown in FIG. 6.

These problems may occur not at the L/G switching region but at theheader region existing in the land track or the groove track when theerror is large.

FIG. 5 is a waveform showing an example of a track error that occurswhen sampling and holding the header region existing on switching fromthe land to the groove and FIG. 6 is a waveform showing an example of atrack error that occurs when sampling and holding the header regionexisting on switching from the groove to the land.

Thus, when the servo becomes unstable or a header region exists withinthe same track or on switching from the land track to the groove trackand vice verse, a value of a previous track region is sampled and held,and thereby is inverted, which causes the following problems.

First, since the header region is not detected exactly, a track slidingphenomenon may occur.

Second, a track servo becomes unstable due to a variation of a discretetrack error. Especially, when the variation is serious, a slad servobecomes unstable, too.

Third, the instability of the track servo lowers the characteristics ofthe record and reproduction, thereby having a bad influence on-thequality of the eye pattern and the jitter.

SUMMARY OF THE INVENTION

Accordingly, the present invention is provided to substantially obviateone or more of the problems due to limitations and disadvantages of therelated art.

An object of the present invention is to provide a method and apparatusfor controlling record reproduction of an optical record medium ofperforming the servo using an averaged servo error signal to such adegree that an influence of the header region can be removed at theheader region.

Another object of the present invention is to provide a method andapparatus for controlling record reproduction of an optical recordmedium that perform the servo at the header region by holding a fixed DCoff-set voltage.

Other object of the present invention is to provide a method andapparatus for controlling record reproduction of an optical recordmedium that perform the servo at the header region by holding a servoerror value of the same track.

Further object of the present invention is to provided a method andapparatus for controlling record reproduction of an optical recordmedium that differently perform servos in a header region existing inthe same track and a header region existing on switching of L/G track.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described, a methodfor controlling the record and reproduction of optical record medium inwhich plural non-record regions having different phase are arrangedbetween recordable data regions for the distinction in the shape of thedata region, the method comprising the steps: detecting the non-recordregions; averaging servo error signals that are generated by a lightreflection signal from the optical record medium; selectively outputtingthe averaged servo error signal at the non-record region and outputtinga servo error signal prior to being averaged at a region other than thenor-record region; and performing servo using the servo error signals.The averaging step comprises a step of low pass filtering the servoerror signal and averaging the filtered servo error.

According to another aspect of the present invention to accomplish theobjects and advantages, there is provided a method for controlling therecord and reproduction of optical record medium, the method comprisingthe steps of: detecting the non-record regions; selectively outputting afixed DC off-set voltage as a servo error signal at the non-recordregion and outputting a servo error signal that is generated using alight reflection signal from the optical record medium at a region otherthan the nor-record region; and performing servo using the servo errorsignals.

The DC off-set voltage in the servo error signal outputting step becomedifferent depending on whether a track where the non-record region isplaced is a land or a groove.

The DC off-set voltage in the servo error signal outputting step is thesame regardless of whether a track where the non-record region is placedis a land or a groove.

According to another aspect of the present invention to accomplish theobjects and advantages, there is provided a method for controlling therecord and reproduction of optical record medium, the method comprisingthe steps of: detecting the non-record regions; selectively outputting aservo error signal of previous same track region at the non-recordregion, the servo error signal being sampled and hold and outputting aservo error signal that is generated using a light reflection signalfrom the optical record medium at a region other than the nor-recordregion; and performing servo using the servo error signals.

The servo error signal outputting step comprises a step of outputting anaverage value of a servo error signal of a present track when thenon-record region exists within the same track and outputting an averagevalue of a servo error signal of a previous same track region when thenon-record region exists at the track shift region.

According to another aspect of the present invention to accomplish theobjects and advantages, there is provided a method for controlling therecord and reproduction of optical record medium, the method comprisingthe steps of: detecting the non-record regions; selectively outputtingone from among a servo error signal that is low pass filtered, a fixedDC off-set voltage, an average value of previous same track region asthe servo error signal at the non-record region and outputting a servoerror signal that is generated using a light reflection signal from theoptical record medium at a region other than the nor-record region; andperforming servo using the servo error signals.

According to another aspect of the present invention to accomplish theobjects and advantages, there is provided a method for controlling therecord and reproduction of optical record medium, the method comprisingthe steps of: detecting the non-record regions; determining whether thenon-record region exists within a same track or at a track shift regionand outputting a control signal according to the determined result; anddifferently performing a servo control in non-record regions that existwithin the same track and at the track shift region.

According to another aspect of the present invention to accomplish theobjects and advantages, there is provided an apparatus for controllingthe record and reproduction of optical record medium, comprising: adetecting part for detecting the non-record regions to output thedetected non-record region detecting signal a header control part forselectively outputting one from among a servo error signal that is lowpass filtered, a fixed DC off-set voltage, an average value of servoerror signals of previous same track region as the servo error signal atthe non-record region and outputting a servo error signal that isgenerated using a light reflection signal from the optical record mediumat a region other than the nor-record region; and a servo part forperforming servo using the servo error signals output from the headercontrol part.

Additional features and advantages of the invention will be set forth inthe description which follows, and in part will be apparent from thedescription, or may be learned by practice of the invention. Theobjectives and other advantages of the invention will be realized andattained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

In the drawings:

FIG. 1 is a block diagram of a general optical record and reproductionapparatus;

FIG. 2 is a schematic diagram showing an example of the optical detectorof FIG. 1;

FIG. 3 is a schematic view showing the arrangement of the header that ispre-formatted at the initial position of each sector in a generalrewritable disc;

FIG. 4 is a waveform showing a general example sampling and holding atracking error value in the header region of FIG. 3;

FIG. 5 is a waveform showing an example of a track error that isgenerated on sampling and holding the header region existing onswitching from the land to the groove;

FIG. 6 is a waveform showing an example of a track error that isgenerated on sampling and holding the header region existing onswitching from the groove to the land track;

FIG. 7 is a block diagram of an apparatus for controlling recordreproduction of an optical record medium in accordance with oneembodiment of the present invention;

FIG. 8 is a detailed block diagram of an apparatus for controllingrecord reproduction of an optical record medium in accordance withanother embodiment of the present invention;

FIG. 9 a to FIG. 9 e are waveforms showing the servo control procedureof the header region in the optical record reproduction apparatus inaccordance with the present invention;

FIG. 10 is a detailed block diagram of an apparatus for controllingrecord reproduction of an optical record medium in accordance with stillanother embodiment of the present invention;

FIG. 11 is a waveform showing an example sampling and holding thetracking error value in the header region on the switching of the L/Gtrack in accordance with further still another object of the presentinvention; and

FIG. 12 is a block diagram of an apparatus for controlling recordreproduction of an optical record medium in accordance with yet stillanother embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings.

Hereinbelow, preferred embodiments in accordance with the presentinvention are described with reference to the accompanying drawings.

The present invention performs a focus servo and a tracking servo byholding one from among an averaged servo error to such a degree that theinfluence of the header can be removed at the header region, a fixedoff-set voltage, and a servo error signal of previous same tracks.Especially, the invention is more effective when it is applied to theheader region existing on switching of L/G track. In addition, theinvention employs a combination of servo control methods in the headerregion or an independent method, to thereby make the servo method in theheader region existing in the same track differently from or equallywith the servo method in the header region existing on the switching ofL/G, which depends on the selection of a designer.

FIG. 7 is a block diagram of an optical record reproduction apparatus inaccordance with the present invention. In FIG. 7, the remaining elementsexcept a header control part 200 is the same with those of FIG. 1.Accordingly, like reference symbols are used for elements having thesame functions and constitutions with those of FIG. 1 and detaileddescription thereof is intentionally omitted.

FIG. 8 is a detailed block diagram of the header control part(200) andFIG. 10 shows an another embodiment of the header control part 200.Specifically, FIG. 8 shows that the servo is performed by an averagedservo error signal to such a degree that the influence of the header canbe removed at the header region.

Referring to FIG. 8, the header control part 200 comprises: a first lowpass filter(LPF) 301 for low pass filtering a focus error signaldetected in the RF & servo error generating part 103; a second LPF 302for low pass filtering a tracking error signal; and a selection part 303that selects a focus error signal and a tracking error signal which arelow pass filtered through the first LPF 301 and the second LPF 302 or afocus error signal and a tracking error signal that by-pass the firstLPF 301 and the second LPF 302 and outputs the selected signals to theoff-set control part 105.

In the above constituted one embodiment, the header control part 200holds respective servo error signals, for example, tracking errorsignal(TE) and focus error signal(FE) at the header region. This holdingoperation is performed not at a previous sample level like theconventional manner but at a signal level that is low pass filtered tosuch a degree that the influence of the header can be removed, therebydecreasing the influence of the header.

To this end, the header mask & L/G switching signal generating part 106generates the header mask signal(HDM) representing a header region usingRF signal, R-ch2, IP1 signal, IP2 signal, etc., that are provided by theRF & servo error generating part 103, and generates the L/G switchingsignal(L/Gsw) with the determination on which one of the IP1 and IP2signals precedes.

Meanwhile, the first LPF 301 removes an RF component from the focuserror signal output from the RF & servo error generating part 103 andaverages the RF component-removed focus error signals. The second LPF302 removes an RF component from the tracking error signal output fromthe RF & servo error generating part 103 and averages the RFcomponent-removed tracking error signals. Here, the bandwidth of thefirst and second LPFs 301 and 302 is set to such a degree that theinfluence of the header can be nearly removed.

The selection part 303 selects the focus error signal and the trackingerror signal which are low pass filtered by the first and second LPFs301 and 302, respectively as the header mask signal(HDM) representingthe header region is output from the header mask & L/G switching signalgenerating part 106, i.e., at the header region, and outputs theselected signals to the off-set control part 105, while the selectionpart 303 selects a focus error signal and a tracking error signal thatby-pass the first and second LPFs 301 and 302 and outputs the selectedsignals to the off-set control part 105 in cases other than the abovecircumstance, i.e., at the record region.

FIG. 9 a to FIG. 9 e are waveforms showing a holding procedure of thetracking error signal, in which the header region of FIG. 9 a isexpressed as a head mask signal(HDM) shown in FIG. 9 e. FIG. 9 d is anexample of L/G switching signal and shows that the header region isplaced at the shift region of L/G track. At this time, since the headerregion is a non-record region, a tracking error signal is largelygenerated at the header region as shown in FIG. 9 a. Thus, in case thatthe tracking error signal in the header region of FIG. 9 a is low passfiltered through the second LPF 302, the filtered tracking error signalis averaged as shown in FIG. 9 b. In other words, the tracking errorsignal is output with a shape adjacent to the linear line even at theheader region. Thus, although the focus error signal and the trackingerror signal are not held to a previous value, the servo is hardlyinfluenced by the header.

Especially, on switching of L/G, for example, although the L/G switchingoccurs at the mid portion of the header region and thus the trackingerror signal bounces, this bouncing degree is a negligible quantity. Inaddition, although the L/G switching occurs at the initial stage of theheader region and the tracking error signal bounces, the servo follows adesired track using an LPF. And, in case that when the header region isended, the L/G switching occurs and thus the tracking error signalbounces, the light beams do not deviate from the track center since theservo follows the track using the LPF.

The subsequent operations, i.e., the operation after the off-set controlpart 105 is the same with that of FIG. 1 and thus is intentionallyomitted.

Thus, the present invention can perform the focus servo and the trackingservo that are low pass filtered at the header region regardless of theheader region within the same track and the header region existing onthe L/G switching. Also, at the header region within the same track, theservo error value right before the header region starts is sampled andheld to perform the focus servo and the tracking servo like theconventional art. At the header region existing on the L/G switching,the focus servo and the tracking servo can be performed using the servoerror signal that is low pass filtered, which depends on the selectionof a designer.

Meanwhile, FIG. 10 shows a constitution of the header control part 200in accordance with another embodiment of the present invention and theheader control part 200 has features that at the header region, a fixedDC off-set value is held or an average value of the focus error signaland the tracking error signal in the previous same track is sampled andheld.

Referring to FIG. 10, the header control part 200 comprises: a focussampling & holding part 401 for holding a sampling value of a previouslydetermined focus error signal at the header region; a selection part104-3 that selects a focus error signal and a tracking error signalwhich are sampled and held by a focus sampling & holding part 401 and atracking sampling & holding part 402, respectively depending on a headermask signal(HDM) that is output from a header mask & L/G switchingsignal generating part 106 or a focus error signal and a tracking errorsignal that by-pass the focus sampling & holding part 401 and thetracking sampling & holding part 402 respectively and outputs theselected signals to the off-set control part 105; and a sampling valuedetermining part 404 for determining a sampling value that is held bythe focus sampling & holding part 401 and the tracking sampling &holding part 402, respectively.

In the above-constituted embodiment, the header control part 200 holdsthe sampling value that is determined within the header region by thesampling value determining part 404 and allows the light beam not to bedeviated from the track center.

In other words, the focus sampling & holding part 401 fixes the samplingvalue at a reference level, i.e., DC off-set voltage(for example, 2V)depending on the control of the sampling value determining part 404 andperforms the focus servo using the fixed DC off-set voltage at theheader region. Also, the tracking sampling & holding part 402 fixes thesampling value at a reference level, i.e., DC off-set voltage(forexample, 2V) depending on the control of the sampling value determiningpart 404 and performs the tracking servo using the fixed DC off-setvoltage at the header region. As a result, the track error after passingthrough the header region is decreased.

Thus, the present invention can perform the focus servo and the trackingservo using the fixed off-set voltage at the header region regardless ofthe header region within the same track and the header region existingon the L/G switching. In addition, the invention may perform the focusservo and the tracking servo at the header region by sampling andholding the servo error value right before the header region starts likethe conventional art and at the header region existing on the L/Gswitching by the fixed DC off-set voltage, which depends on theselection of a designer.

Here, in case of the header region existing on the L/G switching, theinvention may employ the same off-set voltage at the switching from thegroove to the land and vice versa or may employ different off-setvoltage.

In other words, since DC off-sets in the land and the groove aredifferent due to the depth difference between the land and the groove,the header control part 200 can hold the servo error value with the DCoff-set voltage of the groove in case of switching from the land to thegroove and with the DC off-set voltage of the land in case of switchingfrom the groove to the land.

Meanwhile, the header control part 200 may hold an average value of thefocus error and the tracking error in the previous same track region asa sampling value at the header region instead of holding a fixed DCoff-set voltage.

Likewise, the present invention can perform the focus servo and thetracking servo with a sampling value that is an average value of thefocus error and the tracking error in the previous same track regionregardless of the header region within the same track and the headerregion existing on the L/G switching. Also, at the header region withinthe same track, the servo error value right before the header regionstarts is sampled and held to perform the focus servo and the trackingservo like the conventional art. At the header region existing on theL/G switching, the focus servo and the tracking servo can be performedwith a sampling value that is an average value of the focus error andthe tracking error in the previous same track region, which depends onthe selection of a designer.

The invention in case of the header region existing on the L/G switchingstores an average value of averaging the focus error value and thetracking error value in the previous same track region at a constantregion and can hold the stored value at the header region on switchingof the land/the groove. Here, the invention can store and hold the focuserror value and the tracking error value in the right previous sametrack region instead of the average value.

For instance, assuming that the switching is performed from the land tothe groove and at this time there exists a header region, each averagevalue of the focus error value and the tracking error value of thestored previous groove is sampled and held. Thus, the average value ofthe same track region is held, thereby removing a track error onswitching of the land/the groove.

Also, assuming that the switching is performed from the present grooveto the land, each average value of the focus error value and thetracking error value of the stored previous land is sampled and held.

Thus, the focus sampling & holding part 401 and the tracking sampling &holding part 402 of the header control part 200 at the header regionexisting on the L/G switching hold the DC off-set voltage fixed by thecontrol of the sampling value determining part 404 or hold the servoerror value of the previous same track region.

At this time, the selection part 403 selects the focus error signal andthe tracking error signal which are held by the focus sampling & holdingpart 401 and the tracking sampling & holding part 402, respectively asthe header mask signal(HDM) representing the header region is outputfrom the header mask & L/G switching signal generating part 106, i.e.,at the header region, and outputs the selected signals to the off-setcontrol part 105. And, the selection part 403 in cases other than theabove circumstance, i.e., at the record region selects a focus errorsignal and a tracking error signal that by-pass the focus sampling &holding part 401 and the tracking sampling & holding part 402 andoutputs the selected signals to the off-set control part 105.

A focus off-set control part 105-1 of the off-set control part 105receives the focus error signal output from the selection part 403 andadjusts the focus error off-set to the groove/the land such that thenormal focus servo is performed. Also, the tracking off-set control part105-2 receives the tracking error signal output from the selection part403, adjusts the tracking error off-set to the groove/the land andinverts the tracking error signal detected in the land such that thenormal tracking servo is performed.

A servo control part 107 converts the value output through the off-setcontrol part 105 into a focus driving signal and a tracking drivingsignal, respectively and a servo driving part 108 operates a focusactuator and a tracking actuator within the optical pickup, respectivelydepending on the focus driving signal and the tracking driving signal.

As another embodiment of the present invention, as shown in FIG. 12, aheader control part comprises a first header control part 601, a secondheader control part 602 and a selection part 603.

The header control part in accordance with the present embodiment cancontrol a focus tracking servo and a tracking servo independently in aheader region existing in the same track and in a header region existingon the L/G switching. For example, the first header control part 601controls the focus servo and the tracking servo in the header regionwithin the same track and the second header control part 602 controlsthe focus tracking servo and the tracking servo in a header regionexisting on the L/G switching. At this time, the header mask & L/Gswitching signal generating part 106 determines whether the presentheader region is the header region within the same track or the headerregion existing on the L/G switching, and outputs the determined resultas a selection signal to the selection part 603. Then, the selectionpart 603 selects the output of the first header control part 601 or theoutput of the second header control part 602 depending on the selectionsignal of the selection part 603 and outputs the selected outputs to theoff-set control part 105. Here, the selection part 603 can be made of amultiplexer or may comprises a switching element.

Assuming that the first header control part 601 controls the servo ofthe header region within the same track and the second header controlpart 602 controls the servo of the header region existing on the L/Gswitching, the first header control part 601 can be made of one fromamong the header control part of FIG. 8, the header control part of FIG.10 and the header control part of the conventional art and the secondheader control part 602 can be made of either the header control part ofFIG. 8 or the header control part of FIG. 10, which depends on theselection of a designer.

This is to differently control the servo of the header region within thesame track and the servo of the header region existing on the L/Gswitching. Thus, when it is requested that the same control method beapplied, any one of the header control parts of FIG. 8 and FIG. 10 isused.

As one example, the servo at the header region within the same track isperformed using a servo error signal that is low pass filtered and theservo at the header region existing on the L/G switching is performed bya fixed DC off-set voltage or holding the servo error value of theprevious same track region. In addition, the servo at the header regionwithin the same track is performed using a servo error signal that islow pass filtered and the servo at the header region existing on the L/Gswitching is performed by holding an average value of the servo errorsignals of the previous same track region.

As described previously, the method and apparatus for controlling recordreproduction of optical record medium according to the present inventionperforms the servo using focus error signal and tracking error signalaveraged by the low pass filter at the header region of the opticaldisc. Especially, the tracking servo is performed by holding a fixed DCoff-set value at the header region existing on the L/G switching orholding the tracking error value of the previous same track region. As aresult, the exact header region is detected, the track slidingphenomenon is removed, and the tracking servo is stabilized, resultingin preventing the degeneration of the record and reproductioncharacteristics.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the apparatus and method forcontrolling the record and reproduction of optical record mediumaccording to the present invention without departing from the spirit orscope of the invention. Thus, it is intended that the present inventioncovers the modifications and variations of the invention provided theycome within the scope of the appended claims and their equivalents.

1. A method for controlling the record and reproduction of opticalrecord medium in which plural non-record regions having different phaseare arranged between recordable data regions for the distinction in theshape of the data region, the method comprising the steps: detecting thenon-record regions; selectively outputting a fixed DC off-set voltage asa servo error signal at the non-record region and outputting a servoerror signal that is generated using a light reflection signal from theoptical record medium at a region other than the nor-record region; andperforming servo using the servo error signals.
 2. The method of claim1, wherein the DC off-set voltage in the servo error signal outputtingstep become different depending on whether a track where the non-recordregion is placed is a land or a groove.
 3. The method of claim 1,wherein the DC off-set voltage in the servo error signal outputting stepis the same regardless of whether a track where the non-record region isplaced is a land or a groove.
 4. A method for controlling the record andreproduction of optical record medium in which plural non-record regionshaving different phase are arranged between recordable data regions forthe distinction in the shape of the data region, the method comprisingthe steps: detecting the non-record regions; selectively outputting aservo error signal of previous same track region at the non-recordregion, the servo error signal being sampled and hold and outputting aservo error signal that is generated using a light reflection signalfrom the optical record medium at a region other than the nor-recordregion; and performing servo using the servo error signals.
 5. Themethod of claim 4, wherein the servo error signal outputting stepcomprises a step of outputting an average value of a servo error signalof a present track when the non-record region exists within the sametrack and outputting an average value of a servo error signal of aprevious same track region when the non-record region exists at thetrack shift region.
 6. A method for controlling the record andreproduction of optical record medium in which plural non-record regionshaving different phase are arranged between recordable data regions forthe distinction in the shape of the data region, the method comprisingthe steps: detecting the non-record regions; selectively outputting onefrom among a servo error signal that is low pass filtered, a fixed DCoff-set voltage, an average value of previous same track region as theservo error signal at the non-record region and outputting a servo errorsignal that is generated using a light reflection signal from theoptical record medium at a region other than the nor-record region; andperforming servo using the servo error signals.
 7. A method forcontrolling the record and reproduction of optical record medium inwhich plural non-record regions having different phase are arrangedbetween recordable data regions for the distinction in the shape of thedata region and a first track and a second track having different depthsalong light incident direction are alternatively arranged, the methodcomprising the steps: detecting the non-record regions; determiningwhether the non-record region exists within a same track or at a trackshift region and outputting a control signal according to the determinedresult; and differently performing a servo control in non-record regionsthat exist within the same track and at the track shift region.
 8. Themethod of claim 7, wherein the servo performing step performs the servoat the non-record region existing within the same track by holding aservo error signal that is low pass filtered and at the non-recordregion existing at the track shift region by holding a fixed DC off-setvoltage.
 9. The method of claim 8, wherein the DC off-set voltage of theservo performing step becomes different depending on whether the shiftedtrack is the first track or the second track.
 10. The method of claim 8,wherein the DC off-set voltage of the servo performing step is the sameregardless of the shift of the track.
 11. The method of claim 7, whereinthe servo performing step performs the servo at the non-record regionexisting within the same track using a servo error signal that is lowpass filtered and at the non-record region existing at the track shiftregion using an average value of servo error signals of previous sametrack region.
 12. The method of claim 11, wherein the servo performingstep performs the servo with an average value of the previously samesecond track at the non-record region existing at the track shift regionwhen it is determined that the track is shifted from the first track tothe second track.
 13. The method of claim 11, wherein the servoperforming step performs the servo with an average value of thepreviously same first track at the non-record region existing at thetrack shift region when it is determined that the track is shifted fromthe second track to the first track.
 14. An apparatus for controllingthe record and reproduction of optical record medium, the optical recordmedium having a land track and a groove track, in which pluralnon-record regions having different phase are arranged betweenrecordable data regions for the distinction in the shape of the dataregion, the apparatus-comprising: a detecting part for detecting thenon-record regions to output the detected non-record region detectingsignal; a header control part for selectively outputting one from amonga servo error signal that is low pass filtered, a fixed DC off-setvoltage, an average value of servo error signals of previous same trackregion as the servo error signal at the non-record region and outputtinga servo error signal that is generated using a light reflection signalfrom the optical record medium at a region other than the nor-recordregion; and a servo part for performing servo using the servo errorsignals output from the header control part.
 15. The apparatus of claim14, wherein the servo part comprises: a shift signal output part foroutputting a shift signal of the land/the groove when the shift of theland/the groove is confirmed; a land off-set control part for off-setcontrolling the servo error signal output through the header controlpart to be appropriate for the land and inverting a tracking errorsignal of the servo error signal; a groove off-set control part foroff-set controlling the servo error signal output through the headercontrol part to be appropriate for the groove; an error signal outputpart for selectively outputting either the servo error signal that isoff-set controlled to be appropriate for the land step or the servoerror signal that is off-set controlled to be appropriate for the groovedepending on the shift signal; and a servo control part for performingthe servo using the servo error signals output selectively.